1. Field of the Invention
This invention relates generally to tow bars, and more particularly to an A-frame type tow bar apparatus that provides superior strength and durability while maintaining a great range of motion between the towed-vehicle relative to the towing-vehicle.
2. Description of Related Art
Tow bars that bolt directly onto a towing vehicle for towing a towed vehicle also well known in the prior art. Examples of such tow bars are shown in Parent, U.S. Pat. No. 5,765,851, and Johnson, U.S. Re. Pat. No. 35,482, which are described in greater detail below. While these tow bars are superior to a ball hitch, these tow bars are both bulky and relatively expensive to manufacture. To provide the flexibility necessary to allow the towed vehicle a range of motion relative to the towing vehicle, most prior art tow bars include three hinged connections, one hinge providing flexibility in the horizontal plane, a second hinge providing flexibility in the vertical plane, and a third hinge that provides a pivotal point for twisting. While these hinges are functional, they are also weak points in the tow bar that could break under rigorous conditions.
It is also known to substitute at least one of the hinged connections with a ball-and-socket connection. Examples of this are shown in R. E. Moore, U.S. Pat. No. 2,139,970 and J. E. Powell, U.S. Pat. No. 1,185,435.
W. W. Cushman, U.S. Pat. No. 2,916,301, teaches warehouse tractors and the like and has for its primary object to so modify the pusher plate on such vehicles that the latter may be readily connected together as a train and be pulled to and from the place of work by a leading vehicle. While Cushman teaches the use of a pair of bars that terminate in hemispheres that can be joined to form a single unit, the hemispheres of Cushman are not positioned within a call-and-socket connection. In Cushman, the hemispheres are part of a jack mechanism that merely push against a half-socket for the purposes of depressing the drawbar tongue and raising the tractor. Cushman does not teach the combination of two hemispheres within a complete socket to form a ball-and-socket connection that can withstand both pushing and pulling forces.
W. La Hodny, U.S. Pat. No. 2,071,883, teaches a ball-and-socket connection that is used in the field of rear view mirrors. To the extend Hodney is instructive of the present invention, it would not be obvious to apply the teachings of this field to the field of towing vehicles. Rear view mirrors are adapted to bind in a certain xe2x80x9chold position,xe2x80x9d and the connection does not have to be very strong. Designs that might be highly adjustable and functional for rear view mirrors would not often be capable of withstand the rigorous pushing and pulling strains that are placed on a tow bar apparatus.
Parent, U.S. Pat. No. 5,765,851, teaches a storable self-aligning towing assembly which allows universal pivoting about three axes between a towing vehicle and a towed vehicle. The towing assembly is self-supporting. A hitching member is releasably attached to a towing vehicle at a first end of the hitching member; a first yoke member is pivotally attached to a second end of the hitching member such that the first yoke member pivots about a first axis which is generally horizontal and is normal an extended longitudinal axis of the hitching member; a second yoke member is connected to the first yoke member such that the second yoke member is free to rotate with respect to the first yoke member about an axis that is generally parallel to an extended longitudinal axis of the hitching member; a towed vehicle attachment means is releasably attached at a first end to a towed vehicle; the towed vehicle attachment means is pivotally attached to the second yoke member such that the second yoke member pivots with respect to the towed vehicle attachment means about a second axis which is generally vertical axis and is normal to the extended longitudinal axis of the hitching member. The configuration allows the towing assembly to pivot from a towing position to a storage position on the rear of the towing vehicle. A latching mechanism secures the self-aligning towing assembly in the storage position on the rear of the towing vehicle. The self-aligning towing assembly may be further converted into a shipping position.
Johnson, U.S. Re. Pat. No. 35,482, teaches a towing hitch including a frame having a forward portion selectively connected to the receiver hitch of a towing vehicle, and a rearward portion having a pair of elongated bars pivotally connected thereto for removable connection to a vehicle to be towed. Each bar has a pivot arm connected to the rearward end thereof said pivot arms and bars all to the rearward end thereof, said pivot arms and bars all pivotal within a single plane, so that the pivot arms may be folded into a storage position adjacent and parallel to the bars. Selective locking apparatus permits the pivot arms to be extended to a towing position aligned with the bars and locked in the towing position. The bars are pivotally connected to a pivot block which is pivotally mounted to the forward portion of the frame, so as to permit the pivot block, and attached bars and arms to pivot from a generally horizontal position to a generally vertical storage position. The pivot block is mounted on a rotatable yoke, such that the bars and pivot arms are rotatable, as a unit, along an axis parallel to the direction which a vehicle is being towed.
Hobrath, U.S. Pat. No. 5,909,887, teaches a sulky for a self propelled lawn mower, the sulky being interconnected by a pivot frame and a horizontal pivot to the mower frame, and a vertical pivot between the sulky frame and wheels in order to retain the operator in a constant position in respect to the mower under all operator conditions.
The patents described above are hereby incorporated by reference in full.
The prior art teaches tow bars with flexibility between the towed and towing vehicle. However, the prior art does not teach a tow bar having ball-and-socket connections at one end and a ball joint rod end at a second end that together allow a towed vehicle a great range of motion relative to the towing vehicle, while still providing a strong connection that will not break even under rigorous towing and braking conditions. The present invention fulfills these needs and provides further related advantages as described in the following summary.
The present invention teaches certain benefits in construction and use which give rise to the objectives described below.
The present invention provides a tow bar apparatus that allows a towing vehicle to tow a towed vehicle. The tow bar apparatus includes a pair of tow bars, a means for connecting a first end of each of the pair of tow bars to the towed vehicle, and a means for connecting a second end of each of the pair of tow bars to the towing vehicle. The means for connecting the first end to the towed vehicle may include a pair of socket members adapted to be attached to the towed vehicle. The pair of socket members preferably each includes a girdle around a sidewall. The girdle is adapted to support the sidewall to prevent the sidewall from bending out of shape under the stress of towing. The girdle preferably includes a first bolt aperture opposite the bar slot of the sidewall. An attachment portion has a second bolt aperture through an ear portion and is pivotally connected to the girdle with a pivot bolt. The attachment portion is adapted to be attached to the towed vehicle, thereby enabling the pair of socket members to pivot with respect to the towed vehicle. The means for connecting a second end of each of the pair of tow bars to the towing vehicle preferably includes a pair of ball rod end joints attached to the second ends of the pair of tow bars. Each of the pair of ball rod end joints has an external ring attached to the second end, and an internal ring pivotally mounted within the external ring. The internal ring is adapted to attach securely to the towing vehicle. The internal ring is preferably adapted to be mounted upon a post that is attached to the towing vehicle so that each of the pair of tow bars can rotate and pivot with respect to the towing vehicle.
A primary objective of the present invention is to provide a tow bar apparatus having advantages not taught by the prior art.
Another objective is to provide a tow bar apparatus that allows the towed vehicle a great range of motion relative to the towing vehicle, without weakening the strength of the tow bar.
Another objective is to provide a tow bar apparatus that allows each of the two tow bars to be attached or removed independently of one another, so that the user does not have to lift both of the tow bars at the same time.
A further objective is to provide a tow bar apparatus that includes a pair of tow bars that each terminate in one of a pair of ball rod joint ends that are adapted to be mounted on a post of the towing vehicle.
A further objective is to provide a tow bar apparatus that includes a pair of socket members that enable a removable ball-and-socket connection between the tow bar and the towed vehicle, each of the pair of socket members having a girdle that surrounds and supports a sidewall of the socket members.
A further objective is to provide a pair of socket members that can pivot with respect to the towed vehicle.
Other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.